Glass transition temperatures of copolymers from methyl methacrylate, styrene, and acrylonitrile: binary copolymers

By using a new theoretical glass transition temperature (Tg)–composition equation, Tg’s of statistic binary copolymers obtained from MMA, St and AN were investigated in this article. The copolymers were prepared by bulk copolymerization using azo-bis-isobutyronitrile (AIBN) as initiator. The compositions and Tg’s were determined by NMR and DSC, respectively. The monomer reactivity ratios were obtained by nonlinear fitting with Mayo–Lewis equation. Excellent fitting results were obtained when relations of Tg’s of MMA–St, MMA–AN, and St–AN copolymers with their compositions were investigated by using a new equation which assumed additivity of bond stiff energy (Liu et al. J Phys Chem B 112:93–99, 2008). This equation contains mole fractions of triads and Tg’s of corresponding periodic copolymers. Compared with the widely used Johnston equation and Barton equation, the new equation showed its superiority. Meanwhile, Tg’s of the assumed periodic copolymers that have not been acquired were tentatively predicted which may provide useful information.